I bought to packs of these, and they almost caused me to mess with my guitar tuners. Every thing was fine up till a point maybe a day after i putt them on a guitar, and then i tried a vibrato on some solo on 9 string when i felt i heard a bang, and immediately string stretched a lot, but it didn't break. i tried to tune it but it vent out of tune as soon as i would try to play something on it. It broke after few tries to tune, so i pulled a 9 from my other package and after a day or so it did the same exact thing. That can't be a coincidence.